The present invention relates to a claw coupling.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Claw couplings can find application to transmit a torque between two shafts aligning with one another, such as between a motor shaft and a transmission shaft for example, and include two coupling elements disposed axially opposite one another, having end face surfaces facing towards one another, from which claws engaging alternately into one another project, and a pressure body arrangement disposed between the coupling elements and made of elastic material. The pressure body arrangement includes a ring element and pressure bodies projecting radially outwards from the ring element, which are each received between a claw of one coupling element and a claw of the other coupling element. During operation, the two coupling elements turn relative to one another in accordance with the torque present and the stiffness of the elastic material of the pressure body arrangement. Each claw of the coupling elements executes hereby a rotational movement, with a point of a side surface of a claw disposed radially further out moving on a greater circular track than a point of a side surface of a claw disposed radially further inwards and thereby covering a greater distance. With claw couplings in which the claw surfaces and the pressure body surfaces have curvatures corresponding to one another, this leads to each pressure body being pressed together more on the outside than on the inside, which results in an uneven pressure distribution, in which a higher edge pressure acts radially outwards. Accordingly the pressure bodies are pushed radially inwards during the operation of the claw coupling, which frequently results in a significant deformation of the pressure body arrangement, by which the ring element in particular is effected.
Attempts have been made to prevent this deformation of a pressure body arrangement by limiting the maximum permissible torque of a claw coupling. In this way impermissibly high forces directed inwards acting on the pressure bodies can be prevented, through which a deformation of the ring element of the pressure body ring may be counteracted. The maximum permissible torque is mostly to be set very low here, however, which in many cases is not desirable. Another approach involves replacing the ring element of the pressure body ring by a circular washer, in order to lend a greater stiffness to the arrangement in the radial direction. A drawback of this approach to configure the pressure body arrangement resides in the fact that a shaft can then no longer project into the claw coupling, thereby restricting construction. A further approach involves of selecting the curvatures of the claw surfaces and pressure body surfaces such that the two curvatures each follow a circular track, with the radius of the circular track of the curvatures of the pressure body surfaces being smaller than that of the claw surfaces. As a result, the size of the contact surface between a pressure body surface and an assigned claw surface varying as a function of the torque transmitted by the claw coupling. Accordingly the edge pressing acting on the pressure body can be adjusted by a suitable selection of the radii of curvature of the claw and pressure body surfaces in relation to a rated torque of the claw coupling to be transmitted such that, at the rated torque, comparatively low forces directed radially inwards act on the ring element. However a problem with this approach is that a suitable choice of the respective radii of curvature always involves a series of individual calculations and/or trials, which is associated with very great effort and high costs.
It would therefore be desirable and advantageous to provide an improved claw coupling to obviate prior art shortcomings